It’s a form of negging, and seeing as it’s easy to find a physical flaw on even the cutest person, you can knock her down a peg and gain some cheap power.
Really humiliating her can make her lose status with others, her sense of self, time (she’ll start exercising & obsessive dieting to correct) and focus on her weight instead of gaining power in her life & overtaking men.
Get all women feeling like shit and they’ll starve, freeze, and be hangry constantly, never able to get their shit together and figure out that they’re being manipulated and kept down and used, badly.